Patent GB-802294-A (GB)
Title: Improvements in fuel transfer devices in aircraft
IPC: B64D37/20
Filed: 1956-07-18
Abstract: 802,294. Fuel supply system for tanks. SOC. NATIONALE DE CONSTRUCTIONS AERONAUTIQUES DU SUD-EST. July 18, 1956 [July 22, 1955], No. 22286/56. Class 21. [Also in Group XXIX] A fuel supply system for an aircraft having a common service tank 16, Fig. 3, fed from a number of storage tanks 1, 2, distributed along each wing, comprises an air valve 17, 18 in each storage tank for admitting air under pressure, at least two fuel outlets in each storage tank, such as 5 and 7 in tank 1 and 6 and 8 in tank 2, there being one outlet in each tank on the side nearer the wing tip, and another outlet in each tank on the side nearer the wing root, each outlet being in series with an outlet valve 9, 11, 10 or 12 that closes when the corresponding fuel outlet is not immersed in fuel. This closing action is pneumatically caused by an associated float-actuated needle valve 31, 33, 32 or 34 in a high pressure air circuit; and a pilot float valve 41 in the common service tank 16 that opens or closes as the fuel level in the service tank is lower or higher than a predetermined level, the outlet valves 9, 11, 10 and 12 being servocontrolled by the pilot valve 41 to open by being connected to the air pressure in the service tank 16 when the fuel therein reaches the lower level or to be closed by being connected to said high pressure air circuit when the level in the tank 16 is at the higher level. The system includes a high-pressure air supply pipe 42 for supplying compressed air to the two pressure-reducers 43 and 44, the first of which takes the pressure down to say 1À4 lbs. per sq. inch and this is coupled through a pipe 45 to the air space in the service tank 16 and the second of which lowers the pressure to say 5À7 lbs. per sq. inch and feeds pipes 46 leading to the pilot float valve 41 and each of the float-operated needles valves 31, 32, 33, 34. Outlet valves. Each outlet valve, Fig. 7, has an inlet port 106 and an outlet port 107, the passage therebetween being closeable by a diaphragm operated closure 114. Two diaphragms 122 and 123 couple the closure 114 to the body of the valve and a pipe 128 leading to the space 126 between these diaphragms connects the space 126 to the atmosphere of the service tank 16 and enables any fuel which may have leaked through a cracked diaphragm to flow into the service tank 16. The valve can be permanently closed by inserting a spring 132 into a lower housing 111a but when such a spring is absent the valve is opened or closed depending upon whether the 1À4 air pressure or the 5À7 air pressure is applied to the chamber 130 below the lower diaphragm 123 via a connection 111. Pilot float valve, Fig. 4 and fioat-operated needle valves, Fig. 6. The pilot float valve has an upper port 53 supplied with air at the 5À7 pressure and some lower ports 55 connected to the float-actuated-needle valves 31, 32, 33, 34. When the fuel in the service tank 16 is at its upper level, a float 78 therein is at a height that allows a push rod 71 in the float valve to move to a lower position. The 5À7 pressure air supplied through the port 53 then forces a valve ball 64 down onto a lower seating and the 5À7 pressure air then passes through the lower ports 55 to ports 87 in the float-actuated needle valves, Fig. 6. If the storage tanks 1, 2 are full, the floats 104 of the needle valves cause their needles 90 to close a port 86 in each valve and permit the 5À7 air pressure to pass from the port 87 to a port 85 and thence to the connection 111 in the outlet valve, Fig. 7. The 5À7 air pressure acting under the lower diaphragm 123 causes the outlet valve to close. The 5À7 air pressure is used in the storage tanks 1, 2 to expel the fuel and consequently, since the pressure per sq. in. on the upper diaphragm 122 is therefore equal to that on the lower diaphragm 123 the effective area of the lower diaphragm must be greater than that of the upper diaphragm for the valve to close as stated. The fuel supply to the service tank 16 is thereby stopped. When the fuel in the service tank 16 is at its lower level, the float 78 therein is at a low level that causes the push rod 71 to force the valve ball 64 onto an upper seating to close the port 53 and connect the ports 55 to the 1À4 pressure in the tank 16. This pressure, as before, is transmitted through the float-actuated needle valves to the undersurface of the lower diaphragm 123 in the outlet valves and, as a result, the upper diaphragms 122 acted on by the 5À7 pressure cause the valves to open so that fuel can again flow to the service tank. Whilst fuel is flowing to the service tank the aircraft may bank in such a manner that one or more of the fuel outlets in the storage tanks are uncovered. When this happens the associated floats 104, Fig. 6, fall to a low level and cause their associated needles to move to the left in a manner opening the 5À7 air pressure port 86 and closing the port 87. The 5À7 air pressure passes from the port 86 to the port 85 and thence to the underside of the lower diaphragm 123 in its associated outlet valve to close said valve. Inverted flight. The action of the float 78 of the pilot float valve acts on an upper weighted plate 80 and it is the movements of the plate 80 only that is transmitted to the push rod 71. Thus, when the aircraft is upside down the plate 80, under gravity, will cause the push rod 71 to withdraw from the valve ball 64 and the 5À7 pressure air will again pass from the port 53 to the ports 55 to cause all the outlet valves to close.